jelaskan pengertian to be going to + verb

tobe going to digunakan saat ada kepastian untuk dilakukan di masa depan ..:
contou : the day is going to rain

Artinya "Akan" sama seperti kata WILL..rumusnya
-/Subject + tobe(is am are) + going to + verb1..
contoh : She is going to eat
             Dia akan makan.. (sudah pasti,kalo will biasanya belum pasti)